¹H, ¹³C and ¹⁹⁵Pt n.m.r. spectra of Trimethylplatinum(IV) Tetramers [PtMe₃Z]₄: effects of Pt-Z-Pt and long-range Pt-Z-Pt-C couplings

Abstract

¹H, ¹³C and ¹⁹⁵Pt n.m.r. spectra have been obtained for [PtMe₃(μ₃-Z)]₄ (Z = Cl, Br, I, OH, N₃, SMe, SPh, and SCF₃). The compounds with Z = SPh and SCF₃ have not previously been prepared. In those tetramers which contain more than one ¹⁹⁵Pt nucleus, and where ¹⁹⁵Pt-Z-¹⁹⁵Pt coupling is significant, ¹H and ¹³C spectra cannot be interpreted as first order. Values of ²J_Pt-Z-Pt have been calculated from ¹³C spectra where Z = SMe, SPh, OH, and N₃, and upper limits estimated for a number of other Z. When Z = SMe and OH, long-range ¹⁹⁵Pt-Z-Pt-¹³C coupling is resolved. ²J(¹⁹⁵Pt-S-¹³C) when Z = SMe and SCF₃, and ³J(¹⁹⁵Pt-S-C-¹⁹F) when Z = SCF₃, are unexpectedly small. The ¹⁹⁵Pt resonance frequency decreases in the order Z = OH > SPh > SMe > N₃ ≈ Cl > Br ≈ SCF₃ > I. To assist in analysing the spectra transition frequencies and intensities have been calculated for the AA'₂X spectrum (available as an accessory publication).